Im looking to sell my 91' civic Std and buy a 90-91 Crx HF. My question for you HF gods is this, since the HF has and runs a mpfi motor (d15b8) stock, could I swap out the stock HF motor+ECU and swap in the same year Si motor (d16a6) and pm6 ECU without wiring anything or is there certain changes/mods I would have to make such as wiring,hubs,axles,shift linkage...etc. thanx in advance

 

help!

 

YES

 

Yeah you're going to want to change a few things. It's not terrible if you know what your'e doing but it's not exactly a drop in and go sort of engine.

 

the a6 w/A6 IM is a DIRECT drop in to the HF shell. but you might want to note that talk about the axles to use (assuming that your replacing the trans). find out what year the trans is, then buy those axles (if yours dont fiT).
cause my understanding is that (correct me if im wrong):
Speaking of the trans-side spline count on the axle:
88 Si axles are different from 88 Dx & HF
89-91 HF, DX, Si Axles are the same
As far as the hub side, all 88-91 Hf, Dx, Si Hubs are the same, except Auto Dx i think. But idk. maybe someone can elighten this topic if im incorrect.
But as far as the motor goes, you can drop right in, and so can the ECU. The ECU plugs straight up with no modification. You might also want to make sure that the A6 has a stock or aftermarket header on it. You dont wanna use the HF one.

 

i think all si axles are different than dx and hf. but the 88 si is different from all of them. i have an 88 sucks i had thechance to buy another si tranny with a brand new clutch for cheap, but then id have to source axles too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by undefinedcrx &raquo;</TD></TR><TR><TD CLASS="quote">the a6 w/A6 IM is a DIRECT drop in to the HF shell. but you might want to note that talk about the axles to use (assuming that your replacing the trans). find out what year the trans is, then buy those axles (if yours dont fiT).
cause my understanding is that (correct me if im wrong):
Speaking of the trans-side spline count on the axle:
88 Si axles are different from 88 Dx & HF
89-91 HF, DX, Si Axles are the same
As far as the hub side, all 88-91 Hf, Dx, Si Hubs are the same, except Auto Dx i think. But idk. maybe someone can elighten this topic if im incorrect.
But as far as the motor goes, you can drop right in, and so can the ECU. The ECU plugs straight up with no modification. You might also want to make sure that the A6 has a stock or aftermarket header on it. You dont wanna use the HF one.</TD></TR></TABLE>
correction: The hub end of the axle is what is different. The HF hub/knuckle assy is smaller than the DX/Si. Use your HF axles unless you swap knuckles, then you would need the DX/Si axles. Everything is mostly plug and play. If you get a check engine light, it's not a prob, there are 2 wires on the HF harness that need to be cut at the ECU. These are HF only and will freek the ECU if connected. I cant remember which ones, but has been posted on this board. Also, the HF has an EGR valve, just leave the wiring plug for it disconnected. The black box on the firewall that containes the EGR selenoid, map sensor, and purge selenoid can be removed and Si components substituted, or used as is.
HTH
chris

 

ya u can

 

Si motor with HF tranny won't feel much better than the HF motor you took out.

 

Umm, You will be able to drop everything in, cept your going to have to replace your hub's for a different size spline. Hf's have 2 or 3 less noches' I can't member off the top of my head. So get some axle's and you should have no problem. If you know what your doing and got the tools. It should not take you more then 4 hours maybe 6. I guess it depends how nuts you get lol.

Good Luck!

 

if your not swapping out the HF harness for the SI motor your gonna have to take off the EGR on the HF motor harness

 

youre goingt o have to change spindles and quite a bit of wiring involved too